11th ICRS Abstract book - Nova Southeastern University

26-54
Gene Genealogies Reveal Phylogenetic Species Of Clade C Symbiodinium
Associating With Corals Of The Great Barrier Reef
Dee CARTER* 1 , Katherine LOW 1
1 Molecular and Microbial Biosciences, University of Sydney, Sydney, Australia
Oral Mini-Symposium 26: Biodiversity and Diversification of Reef Organisms
The phylogenetic species concept provides a means of characterising species in
Symbiodinium. The premise behind the phylogenetic species concept is that groups of
individuals that are supported on distinct branches on trees derived from different,
unlinked gene sequences are not exchanging genetic information and may therefore
represent separate species. All phylogenies established for Symbiodinium thus far have
been based on either nuclear or chloroplast ribosomal DNA. However, the establishment
of a comprehensive phylogeny and a consensual nomenclature for Symbiodinium
requires multiple, unlinked markers from the Symbiodinium genome. The aims of this
study were to determine whether clade C Symbiodinium consists of different
phylogenetic speices by 1) developing a suite of molecular markers from Symbiodinium
obtained from fourteen coral species from One Tree Island reef (southern GBR); and 2)
deriving individual and consensual phylogenies from these markers to identify potential
phylogenetic species. Phylogenies were constructed from sequences derived from large
subunit rDNA, psbA, cob and actin genes. Genes trees were for the most part congruent,
with a high number of strongly supported branches, which we propose represent distinct
phylogenetic species of Symbiodinium. Many of these phylogenetic species were
associated with a particular coral host species, suggesting a stable, intimate hostsymbiont
relationship that has developed over a long period of time. The distinct genetic
differences between the different phylogentic species within Symbiodinium are likely to
be associated with differences in physiology, ecology and behaviour. This supports the
assertion that the coral holobiont is a complex assemblage whose partners cannot be
readily substituted, and that coral bleaching may lead to an irreversible loss of coral
biodiversity.
26-55
The Biogeography Of symbiodinium From tridacna Maxima Across The Indo-
Pacific
Michele WEBER* 1 , Scott FAY 1 , Jere LIPPS 1
1 Department of Integrative Biology, University of California Berkeley, Berkeley, CA
Tridacnidae, the giant clams, are one of many groups of host organisms for
Symbiodinium, a diverse clade of symbiotic dinoflagellates that structurally and
energetically support coral reef communities. I collected and sequenced Symbiodinium
from populations of giant clams in the Red Sea, the Indian Ocean and the Pacific Ocean.
Phylogenetic analysis grouped the Symbiodinium into two subgeneric clades, A and C.
The data suggest that there are significant patterns in symbiont biogeography and
biodiversity across the Indo-Pacific. Symbiont populations in Tridacna maxima were
more diverse in the Pacific Ocean than in the Indian Ocean or in the Red Sea. Most
Pacific populations hosted representatives from both Clades A and C and I found
multiple subclade level phylotypes. The samples collected in the Red Sea only hosted
one phylotype from Clade A and the samples from the Indian Ocean hosted one
phylotype of either A or C. According to these data, giant clams are highly specific
implying that they select their symbiont populations to optimize the mutualism. This
study describes Symbiodinium ecology, diversity and biogeography over the complete
distribution of one host species.
26-56
Zooxanthellae Diversity Of The Coral Pocillopora in The Pacific
Helene MAGALON* 1 , Jean-François FLOT 2 , Emmanuelle BAUDRY 3
1 School of Biology, Newcastle University, Newcastle upon Tyne, United Kingdom,
2 Département Systématique et Evolution, Université Pierre et Marie Curie/Museum National
d'Histoire Naturelle, Paris, France, Metropolitan, 3 Laboratoire Ecologie, Systematique et
Evolution, Université Paris Sud, Orsay, France
Coral reefs are threatened by human impacts and global warming, leading to coral bleaching
which involves the loss of the photosynthetic algae (zooxanthellae) living in symbiosis with
corals. Reef resilience after disturbance depends largely on dispersal and colonisation abilities
of corals, and also on the host-symbiont association. We focused on a major species of
Polynesian reefs, the coral Pocillopora meandrina, whose mode of reproduction, dispersal and
zooxanthellae identity were previously unknown.
Using ITS (Internal Transcribed Spacer) sequencing of zooxanthellae inhabiting different
Pocillopora species (P. meandrina, P. verrucosa, P. eydouxi, P. ligulata, P. molokensis, P.
damicornis) collected from different Pacific regions (Hawaii, Japan, French Polynesia and
Tongas), we have shown that (1) Pocillopora hosts a symbiont type which is a generalist and
present across a large geographical area, and (2) P. damicornis shows some flexibility in
symbiosis, probably permitting its association with more thermotolerant zooxanthellae after a
bleaching event and, thus, to better resist temperature rise.
More specifically, the study of P. meandrina symbionts using specific microsatellites shows (1)
a high level of zooxanthellae diversity in symbiosis with P. meandrina, (2) a long-distance
dispersal ability of zooxanthellae, and (3) a lack of correlation between host and symbiont
population structures. This particular host seems to be able to reassociate with new
zooxanthellae strains after a disturbance such as bleaching.
26-57
Diversity of Symbiotic Algae (Zooxanthellae) In Zooxanthellate Corals From Temperate
Japan
Yi-Ting LIEN* 1 , Hironobu FUKAMI 1 , Chaolun Allen CHEN 2 , Yoh YMASHIDA 3
1 Kyoto University, Japan, Wakayama, Japan, 2 Acdemia Sinica, Taiwan, Taipei, Taiwan, 3 Kyoto
University, Japan, Kyoto, Japan
6 types (A-D, F and G) of zooxanthellae (Symbiodinium spp.) have been identified from corals
and clade D has been reported to enhance tolerance of corals to environmental change. In
temperate zone, degree of the environmental change such as irradiance and temperature is much
stronger than that of tropical and subtropical zones. In this study, we focused on the
biogeographic diversity of zooxanthellae associated with reef coral communities in temperate
waters of Japan to address the issue of environmental adaptation.
43 species from 24 genera in the zooxanthellate scleractinian corals were collected from 4 sites
of temperate Japan. Symbiotic algae were isolated from corals and those DNA were extracted.
DNA analyses were done using two markers, nuclear small-subunit ribosomal DNA (nssrDNA)
and nuclear large-subunit DNA (nlsrDNA). The nssrDNA marker was used for restriction
fragment length polymorphism (RFLP) to assay the zooxanthellae clade. The nlsrDNA marker
was used to identify subclade within the zooxanthellae clade.
The RFLP analysis showed that Symbiodinium clade C was dominant in the corals in temperate
zone as well as in tropical and subtropical zones. However there are two exceptions. One is
Alveopora japonica, which distributes limitedly to the temperate zone and harbored
Symbiodinium clades C and F simultaneously. Second, the widespread coral Oulastrea crispata
contained symbionts belonging to clade D. Symbiodinium clades D and F might be speciesspecific
symbionts or play a specific role in temperate zone.
Subclade analysis within clade C using nlsrDNA displayed that Acropora species in temperate
zone harbored subclade C1, whereas some species in tropical zone have been reported to
harbore subclade C3 in previous study. Thus, This study suggests that some coral may change
symbiont composition to adapt temperate zone. Further research such as seasonal change of
symbiont composition is being perused.
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